Clamp for holding drill rods or casings



y 9, 1944' c. s. DAVIDSON CLAMP FOR HOLDING DRILL RODS OR CASINGS FiledJune 12 1942 Patented May 9, 1944 CLAMP FOR HOLDING DRILL RODS OBCASINGS Cecil Stanley Davidson, Falconbridge, Ontario, V

Canada Application June 12, 1942, Serial No. 446,744

3 Claims.

This invention relates to improvements in devices for holding theoperating rods or cables of diamond or other drills used for drillingholes in rocks or soils while extensions are being added or sectionsremoved and which is equally applicable to handling well casings.

The principal objects of the invention are to provide a clamp whichwillefiectively automatically grip the rod, cable or casing when thecutting end has been removed fromthe bottom of a hole so that thelifting device may be uncoupled and sections removed or added as may bedesired, and to provide a clamp which will securely hold anextraordinary load but which will be readily releasable so as to permitimmediate lowering of the drill or casing.

The principal feature of the invention consists in providing a blockwith inclined guideways opening into a central vertical drill orifice inwhich steel balls are housed to project into the central orifice toengage and grip the drill rod, means being provided for engaging saidballs to lift them out of clamping contact with the rod to permit therod to be lowered.

In the accompanying drawing Figure 1 is a plan view of my improved clampwith the cover plate removed.

Figure 2 is a vertical sectional view taken on the line 2-2 of Figure 1.

Figur 3 is a perspective view of the means for unlocking the clamp fromholding contact the drill rod.

Figure 4 is a plan view with the cover removed of a slightly modifiedform of the invention.

Figure 5 is a vertical sectional view similar to Figure 2 showing theclutch balls at the bottoms of the guideways.

In the operation of diamond drills and other forms of drills used indrilling deep holes in rocks or soils it is customary for many hundredsor even thousands of feet of rod or casing to be used and it isnecessary to remove the tool from timeto-time from the bored hole. Whenthis operation is being performed the tool-lifting mechanism can onlymove a limited length of tool out of the hole at one operation and it isnecessary to hold the remaining length of the tool securely fromslipping while the above-ground sections are being removed. The presentinvention has been devised to facilitate this operation.

In the form of the invention as illustrated in Figures 1 and 2 a solidblock I, which is preferably formed of steel but may be of cast metal,is shown in cylindrical form and it is provided with a central,vertical, circular orifice 2, which is with t of slightly largerdiameter than the drill rod; cable or casing with which it is to beused.

The rod or casing 2 is inserted through th central orifice which ispreferably tapered.

Arranged adjacent to the orifice 2 and extending downwardly from the topof the block are a plurality of guideways 3, preferably in the form ofcylindrical orifices, which extend downward and are inclined inwardlytoward the central orifice at a slight angle. The 1ower inner portionsof these orifices open through the wall of the orifice 2. The guideways3 are preferably equally spaced, The bottom 4 of each of the'orifices ispreferably formed of cupped-shape form.

Within each of the guideways 3 is placed a steel ball 5 which is ofslightly smaller diameter than the guideway and will fall to the bottomof the guideway by gravity with the inward part of the perimeterextending into the orifice 2, as shown in Figure 5. Springs 5 may beused to ensure the balls moving into a clutching position even thoughgrease and dirt may get into the ably of quadrangle form as illustratedby dotted lines in Figure 1,

A base plate 9 is secured to the bottom face of the block I and enclosesthe recess 1 and radial opening 8. Within the recess 1 and extending upthrough the circular slot 6 is a ringshaped cam I 0 formed with camsurfaces l l in the upper edge corresponding in number with the numberof guideways 3. A handle I2 is secured to the cam ring l0 and extendsout through the radial slot 8 to provide the means for manipulating thecam.

When the cam is placed so thatthe lower portions of the cam surfaces arein register with the several guideways the balls 5 will drop to thebottom of the guideways and their inner perimeters will thereforeproject into the orifice 2 when there is no drill rod extending throughthe block but when a drill rod is in place the balls will not fall tothe bottom but will engage the drill rod in gripping contact as shown inFigure 2 and the downwardy inclined outer side walls of the guideways 3hold the balls in contact with the rod and the contact of the rodsurface with the balls the weight of the rod forces the balls into tightwedging engagement so that the rod, even though having several tonsweight thereof, will be gripped and held securely from slippingdownwardly into the hole.

When the upper section of the rod has been removed and the liftingmechanism has been again coupled to the rod the upward pull of thelifting mechanism automatically frees the grip of the balls thereon andthe rod moves upwardly freely, but if for any reason the liftingmechanism should slip the rod will be automatically gripped.

It is important that after a section of rod has been added and the drillhas been raised from the bottom of the hole the clamp should be releasedand many conditions arise in drilling operations where it is desirableto let the rod down, and further, it is desirable that the clamp shouldnot be in clamping operation when the drill is being operated to bore.In order to release the rod from the gripping device it is merelynecessary for the operator to manipulate the handle l2, rotate the cam10 within the recess 1, bring the cam surfaces into contact with theunderside of the balls and thus lift them out of clutching contact withthe rod. The rod can be freed in this manner and after having beenallowed to slip a desired distance it can be caught again by simplyoperating the handle l2 to allow the balls to drop down into grippingengagement with the rod.

It is found in practice that this device will grip and holdextraordinary weights even though the movement has accelerated to aconsiderable speed after being released and there is no appreciabledamage to the rod or clamp.

A cover plate [3 is provided which is secured on top of the block I toclose the upper end of the guideways 3 so that the balls will not fallout when the clamp is being handled.

A slight modification of the device is illustrated in Figure 5. Theblock 14 is similar to the block I but it is provided with a radial slotI5 extending out from the central orifice 2 so that instead of the blockhaving to be threaded over the rod it can be slipped into position evenwhen the rod i coupled to the lifting or drilling mechanism.

When a block is formed with an entry slot such as described it will ofcourse be necessary to divide the cam into two parts so that it can beoperated to lift the multiple arrangement of balls. Owing to the slot l5having to open through the cam it will be necessary to provide two ringportions to operate in opposite directions in the guide slot and twohandles l6 and I! are shown.

It will be appreciated that the blocks l or Hi can be made of a veryheavy cross section to withstand any outward pressure that may beapplied thereto by the weight of the drilling tool, and the surfaces ofthe guideways may be tempered or chilled to prevent pitting through theapplied pressure against the balls when heavy loads are checked quickly.

The device is simple and inexpensive to build but is extremely effectivein operation and, as will be readily understood, it can be used invarious diameters and with different numbers of ball grips so that itmay be accommodated to use in handling well casings and cables as Wellas the ordinary drill rod.

What I claim as my invention is:

1. In a clamp for holding drill rods or the like, in which a blockprovided with a central orifice has a plurality of inwardly inclinedguideways extending longitudinally thereof, the lower portions of saidguideways entering said central orifice, said block having a circularslot concentric with the central orifice extending upwardly from thebottom and intersecting the lower ends of said guideways, balls arrangedin said guideways, a cam ring rotatably housed in said slot and havingupwardly extending portions adapted to engage and lift said balls clearof gripping contact with the rod, and means for securing said cam ringin said slot.

2. A clamp for holding drill rods or the like, as claimed in claim 1, inwhich an annular groove is formed in the bottom of said block and isprovided with a radial orifice, the cam ring being rotatable in saidgroove and having a handle extending through said radial orifice, and abase plate closing said annular groove.

3. A clamp for holding drill rods or the like, comprising a block havinga central longitudinal orifice and a radial slot extending out from thecentral orifice, said block having a plurality of inwardly inclinedguideways arranged either side of said slotysaid guideways opening intosaid central orifice, balls arranged in said guideways, a slotconcentric with said central orifice extending upwardly from the bottomof the block and entering the bottom of said guideways, a cam memberrotatably mounted in .said concentric slot having cam portions extendingupwardly to engage the balls in said guideways to lift same clear ofgripping contact with the rod inserted in the central orifice, and meansextending radially from said cam member for rotating same in said slot.

CECIL STANLEY DAVIDSON.

